From 7f1c630a0be7a249506675e66cf37139c4cf7b8c Mon Sep 17 00:00:00 2001
From: Xiang Li <xiang.li@coreos.com>
Date: Tue, 6 Jan 2015 12:09:34 -0800
Subject: [PATCH] *: use keepalive listener to detect dead clients

---
 etcdmain/etcd.go                    |  2 +-
 pkg/transport/keepalive_listener.go | 51 +++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 pkg/transport/keepalive_listener.go

diff --git a/etcdmain/etcd.go b/etcdmain/etcd.go
index 1327ce829..50d759692 100644
--- a/etcdmain/etcd.go
+++ b/etcdmain/etcd.go
@@ -126,7 +126,7 @@ func startEtcd(cfg *config) (<-chan struct{}, error) {
 	clns := make([]net.Listener, 0)
 	for _, u := range cfg.lcurls {
 		var l net.Listener
-		l, err = transport.NewListener(u.Host, u.Scheme, cfg.clientTLSInfo)
+		l, err = transport.NewKeepAliveListener(u.Host, u.Scheme, cfg.clientTLSInfo)
 		if err != nil {
 			return nil, err
 		}
diff --git a/pkg/transport/keepalive_listener.go b/pkg/transport/keepalive_listener.go
new file mode 100644
index 000000000..b33e3ff54
--- /dev/null
+++ b/pkg/transport/keepalive_listener.go
@@ -0,0 +1,51 @@
+/*
+   Copyright 2015 CoreOS, Inc.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package transport
+
+import (
+	"net"
+	"time"
+)
+
+// NewKeepAliveListener returns a listener that listens on the given address.
+// http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/overview.html
+func NewKeepAliveListener(addr string, scheme string, info TLSInfo) (net.Listener, error) {
+	ln, err := NewListener(addr, scheme, info)
+	if err != nil {
+		return nil, err
+	}
+	return &keepaliveListener{
+		Listener: ln,
+	}, nil
+}
+
+type keepaliveListener struct {
+	net.Listener
+}
+
+func (kln *keepaliveListener) Accept() (net.Conn, error) {
+	c, err := kln.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	tcpc := c.(*net.TCPConn)
+	// detection time: tcp_keepalive_time + tcp_keepalive_probes + tcp_keepalive_intvl
+	// default on linux:  30 + 8 * 30
+	// default on osx:    30 + 8 * 75
+	tcpc.SetKeepAlivePeriod(30 * time.Second)
+	return tcpc, nil
+}